In an image forming apparatus using an electrophotographic type or electrostatic recording type process such as a copying machine, a printer, a facsimile machine or a multifunction machine having a plurality of functions of them, the developer is deposited on the electrostatic latent image formed on the image bearing member such as the photosensitive drum to visualize (develop) the electrostatic latent image. A developing device for such development using a two component developer (developer) of a toner, which is non-magnetic particles, and a carrier which is magnetic particles, is known.
In such a developing device, the developer is carried on a surface of a developing sleeve which encloses a magnet, and by rotating the developing sleeve, the developer is fed. An amount of the developer (layer thickness) on the developing sleeve is regulated by a regulating blade as a developer regulating member disposed in proximity with the developing sleeve, and then the developer is fed to a developing zone opposed to the photosensitive drum. Then, the electrostatic latent image formed on the photosensitive drum is developed by the toner in developer.
With such a structure, the amount of the developer fed to the regulating blade may change if the positional relationship between a distribution of a magnetic flux density of the magnet and the regulating blade deviates. Therefore, a proposal has been made in which a magnetic pole disposed opposed to the regulating blade has a substantially symmetrical magnetic flux density, and the position of the regulating blade is displaced from a peak position of the magnetic flux density distribution of the magnetic pole within a half-peak width of the magnetic flux density (Japanese Laid-open Patent Application 2003-140463).
Japanese Laid-open Patent Application 2013-231853 discloses a structure including a guiding member provided upstream of the regulating blade with respect to a rotational moving direction of the developing sleeve to guide the developer toward the developing sleeve.